Ready-to-eat ("R-T-E") breakfast cereals are popular packaged food items. R-T-E cereals exist in large numbers of varieties including puffed and unpuffed, regular or presweetened, and including a wide variety of cereal compositions.
Most R-T-E cereals may be grouped into two broad categories, puffed and unpuffed cereals. Unpuffed cereals include 1) flaked cereals (e.g., corn flakes, wheat flakes, rice flakes, mixed grain flakes), and to a lesser extent 2) shredded whole grains, 3) extruded and other shredded cereals, and 4) granola cereals. The preparation of each of these unpuffed cereal types optionally or essentially comprise a toasting operation. For example, typically, the preparation of flaked cereals essentially comprise toasting the flakes. Conventionally, R-T-E cereal flakes are toasted by oven toasting wet cereal flakes. Flake toasting ovens generally include rotating beds flushed with hot air which gently and evenly toasts the flakes. Flake toasting can also be done by fluidized bed hot air heating. The toasting step generally causes a modest increase in volume (e.g., a two-fold or "2.times." increase) and for this reason this finish step is sometimes referred to as a toasting and puffing step.
Of course, the skilled artisan distinguishes this toasting and puffing step for flake R-T-E cereals from the puffing of puffable R-T-E cereal pellets for the provision of puffed R-T-E cereals. The puffing step for puffed R-T-E cereals employs more rigorous puffing conditions and apparatus that are designed to achieve greater increases in volume, e.g., five-fold to nine-fold ("5.times.-9.times.").
Generally, such known toasting techniques involve intense heating including radiant and/or conduction heating which involve heat transfer from the exterior of the piece inward. Due to the low density of cereal pieces which insulatively resists conductive heat transfer and due to complex shapes, undesirable scorching of the exterior surface, especially at their edges, can occur prior to the development of desirable toasted flavor by any significant part of the interior of the cereal piece.
In the parent application it was surprisingly discovered that methods employing a high intensity microwave energy toasting step provided surprising improvements in finished R-T-E flake products stability and toasted flavor.
In the present invention, a further improvement is provided in the toasting and puffing of R-T-E cereal flakes; namely, the ability to successfully puff relatively thicker R-T-E cereal wet flakes.
In the conventional flake toasting/puffing methods, the upper limit in the thickness of the wet cereal flakes is dependent upon the composition of the cooked cereal dough from which the wet flakes are fabricated. Generally, whole grain cereal flakes are more difficult to puff than wet cereal flakes fabricated from cooked doughs comprising more refined farinaceous ingredients. For example, for a whole grain wheat cereal flake, a thickness of 0.020 inch is generally employed for the wet flake. As the thickness of the wet flake is increased, its ability to puff decreases resulting in progressively hard and dense finished products. An untoasted flake having a starting thickness of 0.025 inch results in a finished flake product of marginal eating qualities. With a starting wet flake thickness of 0.035 inch, the finished product is too hard for consumer acceptance.
However, for wet flakes fabricated from cooked refined cereal doughs comprising more refined carbohydrate materials, thicker flake thicknesses can be used. For products comprising high levels of sugar and added pure starch (i.e., having a protein content of less than 2% and a total dietary fiber content of less than 5%) the wet flake thickness can range up to 0.050 inch and yet yield an acceptable finished R-T-E cereal.
In view of the state of the art, there is a continuing need for improvements in the cereal processing art for preparing R-T-E cereals employing toasting.
Accordingly, in one embodiment of the present invention, the improvement resides in methods for toasting wet thick cereal flakes comprising whole grain cooked cereal doughs having a flake thickness of at least 0.025 inch ranging up to 0.050 inch.
In another embodiment, the present improvement resides in methods for toasting wet, thick cereal flakes comprising refined cooked cereal doughs having a flake thickness ranging up to 0.100 inch.
Accordingly, it is an object of the present invention to provide improved toasting methods for unpuffed or flake R-T-E cereals.
Still another object of the present invention is to provide methods for cereal processing that can be readily practiced in present commercial cereal processing plants without requiring extensive modification of existing cereal processing processes or equipment.
Another object of the present invention is to provide cereal processing method improvements that can be used to toast more evenly irregular and complexly shaped R-T-E pieces.
Another object of the present invention is to provide cereal processing methods that can provide improvements in product stability so as to allow the reduction or elimination of addition of stabilizers to cereal compositions.
Still another object of the present invention is to provide cereal processing methods that can provide toasted unpuffed cereal pieces exhibiting improvements in the evenness of toasting throughout the cereal piece.
Still another object of the present invention is to provide cereal processing methods that can provide toasted flake R-T-E cereal pieces having a relatively greater thickness.
Still another object of the present invention is to provide cereal processing methods that can provide toasted thick flaked R-T-E cereal pieces fabricated from whole grain cooked cereal doughs exhibiting superior volume increases and eating qualities.
Surprisingly, the above objects can be realized and the present invention provides improved methods for dramatically increasing the thickness of wet R-T-E cereal flakes that can be toasted and puffed to provide finished R-T-E flake cereals. The present invention involves subjecting thick wet R-T-E cereal flakes to a brief exposure to a high intensity microwave field. In its product aspect, the present invention resides in improved thick finished flake R-T-E cereals prepared by microwave toasting characterized by interior toasting.
The present invention is an improvement over our prior invention in the realization that the benefits of high intensity microwave heating can be used to puff and tenderize relatively thicker wet R-T-E cereal flakes for flavor and texture development of a wide variety of cooked cereal dough compositions, and especially those comprising whole grain cereals.